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A480 Supernova Remnants 201

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A480 Supernova Remnants 201 Supernova and SuperNova Remnants • We bid a fond farewell to clusters and start a new topic... supernova and supernova remnants 1 Super Nova and Super Nova Remnants • Types of Super Nova • Explosions • Nucleosynthesis • Physics of Supernova remnants • Particle Acceleration • Cosmology? Radio images of SN2008 2 in M82 +Size vs time Supernovae and Supernova Remnants Supernovae • T~ 5000 K effective temperature of photospheric optical emission during early period • most of photon energy is in the is optical and infrared timescale ~ year create a fair fraction of the elements 3 Supernovae and Supernova Remnants Supernova remnants powered by expansion energy of supernova ejecta, dissipated as the debris collides with interstellar material or stellar mass loss generating shocks T ~ 106-7 K characteristic thermal emission is X-rays timescale ~100-10,000 years 4 SNR are multi-wavelength objects •SNR appearance in different energy bands depends on type of SN and the surrounding medium and age –SNR size/morphlogy is not a proxy for age •X-ray-primary shock physics, thermal content, ISM density, ejecta abundances •Optical- secondary shock physics, densities and (occasionally) shock speed and abundances •Radio- particle acceleration • To understand SNRs as a class, high quality data are required at multiple wavelengths 5 Why Study Supernova/Supernova Remnants? Supernova explosion: How is mass and energy distributed in the ejecta? What was the mechanism of the supernova explosion? What and (how much) elements were formed in the explosion, and how? What are the characteristics of the compact stellar remnant? 6 Why Study Supernova/Supernova Remnants? Shock physics: How is energy distributed between electrons, ions, and cosmic rays in the shock? How do electrons and ions share energy behind the shock? 7 Why Study Supernova/Supernova Remnants? Interstellar medium: How is the structure of the interstellar medium affected, and how does the shock interact with that structure? How is the ISM enriched and ionized- how are the metals created and distributed 8 Supernova- sec 4.1-4.3 of Rosswog and Bruggen • Supernova come in two types (I and II) – Type Ia is the explosion of a white dwarf pushed over the Chandrasekar limit- details are not well understood • However they are used as a standard candle for cosmology – Type Ib and II is the explosion of a massive star after it has used up its nuclear fuel- massive M>8M¤ star – Type I supernovae do not show hydrogen in their spectra. Type Ia supernovae reach peak luminosities of about 43 10 4 x10 erg/s (e.g. 10 L¤,MB ~ -19.5 at maximum light,) with very similar light curves • Type II supernovae show hydrogen in their spectra. Their light curves are diverse, with peak luminosities having a wide range ~2x1042-2x1043 erg/s 9 How Massive Stars Explode- T-H Janke 10 • Remember Project ? • Due the week before the last day of classes.. Dec 3 ~10 pages- double spaced- use figures if you want, but not to excess. please cite your references you can use internet resources but must reference them topic of your choice that you are excited about directly related to the class BUT not a topic that we covered in any depth. Original research encouraged but not required 11 SN*types*M*Observa3ons* Optical classifications of SN • I*–*No*H*in*spectrum* – Ia*:**No*He*either,*but* characteris3c*Si*absorp3on* – Ib:**He,*as*well*as* intermediate*mass* elements,*O,*Mg,*Ca*I* – Ic:*No*He,*but* intermediate*elements* • II*–*Strong*H*in*spectrum* – IIMP*:*plateau*in*light*curve* – IIML:*linear*decline*aTer* maximum* K. Long – IIn:*narrow*mul3ple*H*lines* flux vs wavelength near maximum light for Ia and several core collapse (CC) types 8/21/12* Astro*H*M*Kyoto* 12 3* Type Ias appear in all types of galaxies Type Ia supernova, need several very specific events to push white dwarf over the Chandrasekhar limit. Type II and Ib Because massive stars are short lived these supernovae happen in star forming regions – never in elliptical galaxies Type II events occur during the regular course of a massive stars evolution. (adapted from Type Ia Supernovae and Accretion-Induced Collapse Ryan Hamerly) 13 Types of Supernovae Type Ia Type II • No H, He in spectrum Both H, He in spectrum • No visible progenitor (WD) Supergiant progenitor • Kinetic Energy: 1051 erg Kinetic Energy: 1051 erg • EM Radiation: 1049 erg EM Radiation: 1048-49 erg • Likely no neutrino burst ? Neutrinos: 1053 erg • Rate: 1/300 yr in Milky Way Rate: 1/50 yr in Milky Way • Occur in spirals and ellipticals Occur mainly in spiral galaxies • No compact remnant NS or BHs • most of the explosion energy is vast majority of the energy is in in heavy element synthesis neutrino emission and kinetic energy of the ejecta decay of radioactivity keeps it bright for years. 14 Supernova - Summary • Type Ia •Type II • No hydrogen • Hydrogen in spectrum • Thermonuclear explosion of a white • M > 8 solar masses dwarf • Iron core collapses to a neutron star or • No bound remnant • black hole • ~1051 erg kinetic energy • ~1051 erg kinetic energy • • v ~ 2,000 – 30,000 km s-1 • v ~ 5,000 – 30,000 km s-1 • Neutrino burst ~ 3 x 1053 erg • No neutrino burst 49 • Eoptical ~ 10 erg 49 42 -1~ • Eoptical ~ 10 erg • Lpeak ~ 3 x 10 erg s 3 months(varies 43 from event to event) • Lpeak ~ 10 erg s-1 for 2 weeks • Radioactive tail (56Co) • Radioactive peak and tail (56Ni, 56Co) • 2/100 yr in our Galaxy • 1/200 yr in our Galaxy • • Makes about 1/3 iron and all the • Makes about 2/3 of the iron in the oxygen plus many other elements MilkyWay 15 Two Paths to a SNe Ia II 16 The Life of SN1987A- AKA SK-69-202! Progenitor star was a previously catalogued blue supergiant Mass = 18 M¤ 17 How to Get to a Type I • Route to a type I is very complex and not well understood • There maybe several evolutionary paths SN 18 Supernova Explosions Ia Thermonuclear Runaway • Accreting C-O white dwarf reaches Chandrasekhar mass limit (more when we study NS and BHs), undergoes thermonuclear runaway • Results in total disruption of progenitor (no remnant NS or BH) • Explosive synthesis of Fe-group plus some intermediate mass elements (e.g., Si) 19 Type Ia Supernova Explosion Uncertain mechanism and progenitor: probably a delayed detonation* (flame transitions from subsonic to supersonic speed) or deflagration* • Amount of Ni (which drives the long term light curve) synthesized is not the same from object to object èdifferent ejecta mass èdifferent explosion energies èasymmetries in the explosions èdifferences in the explosion physics *Detonation is the violent reignition of thermonuclear fusion in a white dwarf star . It is a runaway thermonuclear process which spreads through the white dwarf in a matter of seconds, *Deflagration-"Combustion" that propagates through a gas or across the surface of an explosive at subsonic speeds, driven by the transfer of heat 20 Type Ia's • Why a thermonuclear explosion of a white dwarf? – Kinetic energy of ejecta ~5x1017 erg/gm (~1/2v2~(104km/sec)2) is similar to nuclear burning energy of C/O to Fe (~1 Mev/ nucleon) – lack of remnant (e.g. NS or BH) or progenitor in both pre and post explosion observations. – occur in elliptical galaxies with no star formation • But (Rosswog and Bruggen pg 136) – No consensus on • mass of WD or its composition before explosion • origin of accreted material (either mass from a 'normal' companion or the merger of 2 white dwarfs) • exact explosion mechanism 21 Type Ia- How the Explosion Occurs • Deflagration wave – Deflagration- "Combustion" that propagates through a gas or across the surface of an explosive at subsonic speeds, driven by the transfer of heat. 8 In main sequence stars Tc~ 10 K to ignite helium core burning- 10 in SNIa Tcore~10 K log temperature 8 9 10 Detailed physics is still controversial! mass shell Fundamental reason: nuclear burning rate in SnIa Deflagration wave in WD conditions ~T12 !! time steps are at 0, 0.6, 0.79, 0 .91, 1.03, 1.12, 'flame' ~ 1cm thick, White dwarf 1.18, 1.24 sec !! 22 has r~108cm Detailed Yields for a SNIa model Abundances are relative Type Ia Nomoto et a; 1984 to solar We will come back to this later.... 23 Type IIs • Collapse of a massive star- the cores mass 'burns' into iron nuclei and has a maximum size determined by the Chandrasekhar limit, ~1.4 M. (see late slides on what this is) • Natural from stellar evolution • Leaves NS or BH or maybe no remnant • Wide range of masses, metallicities, binarity etc make for wide range of properties Lattimer- http://www.astro.sunysb.edu/lattimer/ AST301/lecture_snns.pdf 24 Type IIs • total "optical" energy ~1049erg. • several solar masses ejected at ~1%c • •The kinetic energy ~1051erg Collapse of massive star to a SN- central density reaches ~3x1014 gm/cm3- several times that of nuclear density 25 Type II Progenitors • In a few cases HST has directly observed the progenitor - has to be Progenitor of SN II 2008bk 5 very luminous ~10 L¤to detect before after 26 Elias- Type II Progenitors • In nearby galaxies HST data can constrain the age of the stars near to (50pc)supernova remnants • The most massive stars have shortest lives and explode 'first' – the mass of the oldest living star provides a lower bound to the mass of the star that exploded as a type II SN Estimated mass of progenitor in nearby galaxies 27 Energy Release in Supernovae • Basic idea • Once the core density has reached 1017 -1018 kg m-3 , further collapse impeded by nucleons resistance to compression • Shock waves form, collapse => explosion, sphere of nuclear matter bounces back.
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